A Web site is a directory of files stored on a server or several servers that may be accessed by a client over a network (e.g., the Internet). A Web site contains one or more hypertext markup language (HTML) files called Web pages that are often related or linked to each other. Additionally, a Web site may also contain other types of files such as text files, pictures, movies, sound clips, and so forth. The World Wide Web (Web) is a collection of Web sites whose servers are connected to the Internet. Each Web site in the Web has a unique address, referred to as a universal resource locator (URL), which indicates the protocol required for accessing the Web site and the Internet protocol (IP) address or domain hosting the Web site.
Though the Web contains a vast wealth of information on most every topic imaginable, finding specific information quickly on the Web can be a daunting task. To help with this problem, programs called “search engines” enable users to navigate through the myriad of Web sites on the Web to find the information that they want. A search engine typically has a graphical user interface (GUI) in which a user enters a search query. A search query may include one or more keywords, words to exclude, a phrase, or a sentence. A search query may also specify a language, acceptable file formats, dates, and occurrences of keywords. After receiving a search query, the search engine sorts an index of Web sites and returns a list of URLs of Web sites that are relevant to the search query. A user may become overwhelmed if the number of URLs retrieved by the search engine is very large. Therefore, the user may wish to limit the search results to those Web sites that the user knows and trusts.